Ch. Fetal Central Nervous System Flashcards
The neural tube should be closed by how many weeks?
6 menstrual weeks
Which imaging plane is best to detect spina bifida?
The transverse plane
The sagittal and or coronal plane is used to assess what aspects of the spine?
Cervical and lumbosacral curvatures
sacral caudal tapering
configuration of vertebral ossification centers
The sagittal and or coronal plane is used to assess what aspects of the spine?
Cervical and lumbosacral curvatures
sacral caudal tapering
configuration of vertebral ossification centers
What is the normal limit of the lateral ventricles throughout all of the gestational age?
<10 mm
What is the normal range of measurements for the cisterna magna throughout all of gestational age?
> 3mm and <10mm
What kind of defects occur when there is a failure of the neural tube to completely close by 6 weeks?
Neural tube defects (NTDs)
What is known to decrease a patient’s risk of NTDs?
Folic acid
The most common NTD, occurring more common in females and multiple gestations, it is the congenital absence of the cerebral hemispheres and cranial vault
Anencephaly
Sonographic appearance of anencephaly
“Frog face” sign
absence of the cerebral hemispheres and cranial vault
face and orbits are present
fetal cranium should be present by 12 weeks (15 weeks at the latest)
POLYHYDRAMNIOS (due to ineffective swallowing)
Developmental abnormality in which the cranium is partially or completely absent with the development of abnormal brain tissue, will have elevated levels of MSAFP.
Acrania aka exencephaly
Sono finds of acrania/ exencephaly
Break in the skull with the presence of large amount of brain tissue
reliably demonstrated by 16 weeks as lack of ossified cranium
The herniation of brain and meninges or meninges and CSF (meningocele) through a cranial defect
Encephalocele aka Cephalocele
Where are encephaloceles usually located
Midline, most commonly occipital, may be frontal or lateral
Encephaloceles are associated with what syndrome
Meckel-Gruber syndrome
Sono finds of encephalocele
purely cystic extracranial mass (meningocele)
solid mass contiguous with the cranium (cephalocele)
often associated with hydrocephalus and polyhydramnios
Break in the skull??
Term for lack of closure of the vertebral column, usually occurring in the lumbosacral region
Spina bifida
Herniation of the meninges and CSF through a spinal defect
meningocele
herniation of the meninges AND neural elements (spinal cord) through the spinal defect
Meningomyelocele
Transverse sono finds of spina bifida
Splaying of the posterior elements into a “U” or “V” configuration
when sac is intact, cystic structure may be seen extending from the back
Sagittal sono finds of spina bifida
Splaying of the parallel ossification centers
soft tissue defect or discontinuity or skin and muscle of posterior back
(be aware of normal widening of the spine in the cervical and lumbar regions)
Associated findings in spina bifida are secondary to the —— (what syndrome or condition)
Arnold-Chiari II M=malformation
Intracranial signs of spina bifida
“Lemon” sign - flattening of the temporal/frontal bones due to decreased intracranial pressure
“Banana” sign - obliteration of cisterna magna by abnormal configuration of the cerebellum
hydrocephalus - Lat vent > 10 mm